Respiratory care products, such as those used to provide humid, temperature-controlled oxygen to patients, require a substantially sterile environment for transmitting the oxygen to a patient. In such products, a machine with a pump unit is used to pump water through a fluid circuit including a vapor transfer cartridge that mixes the water with breathing gases (including a specific oxygen percentage) so that the breathing gases being provided to the patient are at a desired humidity level.
In conventional machines, at least a portion of the pump unit is disposable so that the machine is reusable without contaminating the breathing gases supplied to a patient. For example, the pump unit includes a disposable cartridge which is disposed of after each patient use. The disposable cartridge includes rare earth magnets, which are activated by a magnet in the permanent portion (e.g., the capital unit or base unit) of the machine. Activation of the rare earth magnets can cause rotation of an impeller in the disposable cartridge to pump the water through the fluid circuit. While this allows separation between the water in the disposable cartridge and the reusable capital unit of the machine, the disposable cartridges are rather expensive due to the use of rare earth magnets.